地月系L1点的月球借力间接转移轨道设计

针对地月系L1点（LL1）的轨道转移问题,在平面圆型限制性三体问题模型下,提出了利用月球借力的间接转移设计方法.转移设计分为地月转移轨道段和月球至LL1流形段.首先,通过改变LL1点初始机动速度,逆向积分LL1点的拟流形,以寻找初始速度、月心会合坐标系下的轨道高度和相位角这三者之间的关系,确定月球—LL1流形段微分改正的初始条件.然后,借助地月系不同转移时间的霍曼转移轨道所对应的近月点高度和相位角的关系,获得使2段转移在近月点相拼接的地月转移轨道段.这种设计方法给出了一系列LL1点间接转移轨道,将此设计结果与其他文献中的转移设计方法进行比较,此间接转移轨道比低能量转移轨道节省时间,比直接转移轨道节约能量.     

第三只眼看欧洲杯

四年一届的欧洲杯毫无疑问是足球迷的节日,但对于那些对足球远没有达到痴迷程度的人来说,欧洲杯带给他们的更多是一种氛围,是一种生活的调味剂。跟着自己心爱的男人,陪着身边最真挚的亲朋好友一起投身其中,即便不懂足球,又有何妨……     

The Pioneer Anomaly in the Light of New Data

The radio-metric tracking data received from the Pioneer 10 and 11 spacecraft from the distances between 20–70 astronomical units from the Sun has consistently indicated the presence of a small, anomalous, blue-shifted Doppler frequency drift that limited the accuracy of the orbit reconstruction for these vehicles. This drift was interpreted as a sunward acceleration of a _P =(8.74±1.33)×10^?10 m/s² for each particular spacecraft. This signal has become known as the Pioneer anomaly; the nature of this anomaly is still being investigated. Recently new Pioneer 10 and 11 radio-metric Doppler and flight telemetry data became available. The newly available Doppler data set is much larger when compared to the data used in previous investigations and is the primary source for new investigation of the anomaly. In addition, the flight telemetry files, original project documentation, and newly developed software tools are now used to reconstruct the engineering history of spacecraft. With the help of this information, a thermal model of the Pioneers was developed to study possible contribution of thermal recoil force acting on the spacecraft. The goal of the ongoing efforts is to evaluate the effect of on-board systems on the spacecrafts’ trajectories and possibly identify the nature of this anomaly. Techniques developed for the investigation of the Pioneer anomaly are applicable to the New Horizons mission. Analysis shows that anisotropic thermal radiation from on-board sources will accelerate this spacecraft by ～41×10^?10 m/s². We discuss the lessons learned from the study of the Pioneer anomaly for the New Horizons spacecraft.     

重力哪里去了? 神秘的电子推力之谜

今年7月24日的《简氏防务周刊》发表了一篇题为“神秘的推力”的文章,介绍了近年来一些美国和俄国科学家一直在探讨一种能对重力进行控制的推力(升力)发生器,尽管至今没有任何人能对这种现象给以解释,但由于这类研究可能会对航空器的发展带来划时代的影响,并有可能会发展出一种新型武器,所以受到了各国的高度关注,美国NASA、波音公司以及一些知名的研究机构已开始介入研究     

基于信息熵的飞机交流发电机异常检测

以交流发电机的仿真输出电压为参考信号,利用能反映符号序列总体特征的Shannon熵及二进制符号化方法,对仿真出来的正常电压信号及异常电压信号进行二进制符号化分析,并求取符号化后各自的Shannon熵,根据仿真计算表明Shannon熵能够体现由频率引起的电压异常特征。     

The dynamics of the atmospheres of the major planets

The literature on the dynamics of Jupiter's atmosphere is reviewed and used as a basis for suggesting what observations would yield useful information about Jovian Dynamics. The atmospheres of Saturn, Uranus and Neptune are discussed from the same point of view.This is one of the publications by the Science Advisory Group.     

XDLF型流量控制阀的设计

本文介绍了流量控制阀的设计过程和工作原理，并计算了误差精度。本阀具有结构简单、工作可靠，在小流量情况下，工作稳定、精度高的特点。     

The infrared spectrum of the airglow

The techniques of studying the IR airglow are briefly discussed followed by a review of recent observations. The main emphasis is on the molecular emissions of OH and O₂ from the mesosphere and lower thermosphere with a shorter discussion of the F-region atomic emissions. The theoretical interpretations of these emissions are reviewed. It is concluded that dynamic effects must play a dominant and as yet incompletely understood part in the photochemistry of the molecular emission region. An atlas of recently available airglow spectra is included.NRCC No. 13554.     

The loneliness of the long-duration astronaut

This paper investigates the psychological implications of long duration spaceflight. Initial psychological problems associated with a heavy workload were identified during Skylab missions. Since then, most of our knowledge of psychological problems has come from experience onboard Russian spacecraft. Noted problems include anxiety, boredom, crew interactions, problems associated with isolation and confinement, and others. Efforts to alleviate or prevent these problems are discussed, as well as comparisons to similar environments such as arctic regions or submarines. As the U.S. participates in longer space missions, it will be wise to study psychological issues and to learn from our Russian counterparts.     

The ionospheres of the major planets

Physical and chemical processes which affect the equilibrium distribution of ionization in the atmospheres of Jupiter, Saturn, Uranus and Neptune are reviewed. Current models imply readily detectable ionospheres for all four planets and suggest that protons should represent the dominant positive ion. Attention is directed to the probable importance of dissociative ionization of H₂ as a source of H⁺. A number of potentially important loss mechanisms for H⁺ are discussed including a possible reaction of H⁺ with vibrationally excited H₂. Protons may be removed efficiently at lower altitudes by reaction with CH₄ and this process may offer a simple remote means for location of the turbopause.This is one of the publications by the Science Advisory Group.     

The heating of the solar corona

In this paper a discussion is given of the present state of the theory of the heating of the solar corona by shock waves. Arguments are presented why the main contribution to the mechanical energy flux is of acoustic origin, while estimates for the amount of acoustic energy generated in the convection zone as well as the deviations from isotropy are given. During propagation through the atmosphere acoustic waves develop into shock waves after a distance of a few scale heights in the chromosphere. The heating of the outer layers by dissipation of shock waves is found to be sufficient to account for the observed radiative and corpuscular energy losses.Much emphasis is laid on the competitive role played by the four fundamental processes of energy transfer: mechanical heating, radiation, heat conduction and convection of energy in establishing the equilibrium structure of the corona. The atmosphere may be divided in several regions according to the predominance of one of the energy processes mentioned above.The physical properties of the chromosphere and the solar wind are discussed only where they are intimately connected with the problem of the heating of the corona.The most important aspects of the influence of a magnetic field on the structure and the heating of the corona in magnetically active regions are briefly mentioned. Special attention is paid to the strong channelling of heat flow along the field lines and its consequences for the structure and dynamics of the chromosphere-corona transition layer.     

The structure of the Venus ionosphere

Our current knowledge of the spatial structure of the Venus ionosphere and its temporal behavior is reviewed, with emphasis on the more recent Pioneer Venus measurements and analysis not covered in earlier reviews. We will stress the ionosphere structure, since other papers in this issue deal with its dynamics, and its magnetic properties. We also discuss some of the limitations that the orbit has placed on the spatial and temporal coverage of the ionosphere. For the benefit of future users of the data some of the factors which affect the measurement accuracies are discussed in an Appendix.Currently at Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109, U.S.A.     

翼型襟翼受力的稳定性分析

采用数值求解N-S方程的方法,用DES湍流模型求解襟翼高度对风力机专用翼型DU95-W-180气动性能的影响。结果表明,添加一定高度的襟翼后,翼型的受力出现波动现象,而且波动幅度随着襟翼高度的增加而增大,进一步研究引起该现象的原因发现,添加襟翼的翼型其失速旋涡的脱落过程会引起翼型周围压力的周期性变化,进而导致翼型受力出现波动现象。     

The start of the laboratory: the beginnings of the MITInstrumentation Laboratory

The author takes a look at the very early days of the MIT Instruments Laboratory and its successor, the MIT Instrumentation Laboratory. The discussion ranges over some of the incidents and events as these early instrument developers groped with problems that others had already failed to solve, and for which current solutions were declared adequate     

The Geology of Mercury: The View Prior to the MESSENGER Mission

Mariner 10 and Earth-based observations have revealed Mercury, the innermost of the terrestrial planetary bodies, to be an exciting laboratory for the study of Solar System geological processes. Mercury is characterized by a lunar-like surface, a global magnetic field, and an interior dominated by an iron core having a radius at least three-quarters of the radius of the planet. The 45% of the surface imaged by Mariner 10 reveals some distinctive differences from the Moon, however, with major contractional fault scarps and huge expanses of moderate-albedo Cayley-like smooth plains of uncertain origin. Our current image coverage of Mercury is comparable to that of telescopic photographs of the Earth’s Moon prior to the launch of Sputnik in 1957. We have no photographic images of one-half of the surface, the resolution of the images we do have is generally poor (∼1 km), and as with many lunar telescopic photographs, much of the available surface of Mercury is distorted by foreshortening due to viewing geometry, or poorly suited for geological analysis and impact-crater counting for age determinations because of high-Sun illumination conditions. Currently available topographic information is also very limited. Nonetheless, Mercury is a geological laboratory that represents (1) a planet where the presence of a huge iron core may be due to impact stripping of the crust and upper mantle, or alternatively, where formation of a huge core may have resulted in a residual mantle and crust of potentially unusual composition and structure; (2) a planet with an internal chemical and mechanical structure that provides new insights into planetary thermal history and the relative roles of conduction and convection in planetary heat loss; (3) a one-tectonic-plate planet where constraints on major interior processes can be deduced from the geology of the global tectonic system; (4) a planet where volcanic resurfacing may not have played a significant role in planetary history and internally generated volcanic resurfacing may have ceased at ∼3.8 Ga; (5) a planet where impact craters can be used to disentangle the fundamental roles of gravity and mean impactor velocity in determining impact crater morphology and morphometry; (6) an environment where global impact crater counts can test fundamental concepts of the distribution of impactor populations in space and time; (7) an extreme environment in which highly radar-reflective polar deposits, much more extensive than those on the Moon, can be better understood; (8) an extreme environment in which the basic processes of space weathering can be further deduced; and (9) a potential end-member in terrestrial planetary body geological evolution in which the relationships of internal and surface evolution can be clearly assessed from both a tectonic and volcanic point of view. In the half-century since the launch of Sputnik, more than 30 spacecraft have been sent to the Moon, yet only now is a second spacecraft en route to Mercury. The MESSENGER mission will address key questions about the geologic evolution of Mercury; the depth and breadth of the MESSENGER data will permit the confident reconstruction of the geological history and thermal evolution of Mercury using new imaging, topography, chemistry, mineralogy, gravity, magnetic, and environmental data.     

The story of the MIT Radiation Laboratory

The author relates how the MIT Radiation Laboratory came into existence, how it was run, and the research it did during World War II     

The extreme ultraviolet spectrum of the sun

The present state of knowledge of the spectrum of the sun from 3000 Å to 170 Å is critically reviewed. The characteristics of the different photographic and photoelectric spectroscopic instruments and the results are summarized and compared. Topics covered are line identifications, intensities, the continuum and its origin, the sun's surface in Lyman alpha, the profiles of H and K of Mg II, Lyman alpha and beta, and monitoring work conducted from rockets and satellites, including OSO-I.     

轰炸机的发展历程和前景

介绍了轰炸机在各历史阶段发挥的重要作用，分析了轰炸机从诞生到第二次世界大战中发展成熟，以及在冷战时期轰炸机发展的3个阶段。描述了在每个时期不同战场环境下对轰炸机的不同要求，以及由此而产生不同的气动布局形式，进而分析了未来轰炸机发展的3个方向和美国当前可能的型号选择。